Bash regexp.*匹配范围太远 [英] Bash regexp .* matches too far

问题描述

我有一个具有以下内容的文件input.txt:

I have a file input.txt with the following content:

foo
[assembly: AssemblyVersion("1.2.3")]
bar")]
quux

要匹配输入中的 1.2.3 ，请使用以下脚本:

To match the 1.2.3 from the input the following script is used:

#!/bin/bash
regex='\[assembly: AssemblyVersion\("(.*)"\)\]'
fileContent=$(cat input.txt)
[[ "$fileContent" =~ $regex ]]
echo "${BASH_REMATCH[1]}"

我希望输出为 1.2.3 ，但是它是:

I would expect the output to be 1.2.3 but it is:

1.2.3")]
bar

为什么会这样?如何解决?

Why is that so? How to fix it?

位于 https://regex101.com 的正则表达式测试器可以正常工作.

The regular expressions tester at https://regex101.com works as expected.

推荐答案

.* 被称为贪婪点匹配子模式，它与"和)，任何字符包括换行符.

The .* is called a greedy dot matching subpattern and it matches ", and ), any character including a newline.

因此，限制贪婪的最佳技巧是使用否定的字符类 [^] ，该类将匹配除" 以外的任何字符(如果不能包含引号)在带引号的字符串中):

Thus, the best trick to limit the greediness is using a negated character class [^"] that will match any character but " (if there can be no quotes inside the quoted string):

'\[assembly: AssemblyVersion\("([^"]*)"\)\]'
                                ^^^^^ 

演示

或-如果加引号的字符串内不应该包含(和):

or - if there should be no ( and ) inside the quoted string:

'\[assembly: AssemblyVersion\("([^()]*)"\)\]'
                                ^^^^^  

演示

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